Thursday, October 4, 2012

Cover Crops for Profit

Cover crops, or green manure as they are sometimes referred to, are legumes, grasses and brassicas (plants from the mustard family such as cabbage, kale or broccoli). The use of a cover crop can lead to major improvements in the soil, such as increased water infiltration, reduced compaction, and prevention of soil erosion. Long-term use of cover crops is an effective way to increase profit from your farm, and sometimes the cover crop itself can offer a farm product which you can sell.

Crimson Clover

However, the main benefit of continued use of cover crops will be realized in the cash crop that follows the cover crop. This is due to the accumulation of nutrients the cover crop has moved up from lower in the soil profile to the surface layer of soil, which is now available to your next cash crop. Other associated benefits are: suppressing weeds, nitrogen fixing, conserving energy use (less tractor work), conserving moisture, early spring flowers for pollinators, and adding organic matter to improve the soil increasing the vigor of plants.

Legumes are the nitrogen concentrators. The field peas, alfalfa, vetch and clovers will fix nitrogen from the air by the nodules on the roots. When the above ground portion of the plant is chopped down and begins to decompose, the nitrogen is released into the ground. When planting legumes, you should use an inoculant (available commercially) that will help the seedlings form lots of nodules.
Annual Rye Grass

Grasses are the biomass or organic matter builders. Winter Rye, Sudan grass, ryegrass and millet are all grasses that will produce tons of biomass as they are chopped, crimped or rolled down and begin to decompose. Long-term research has documented that fields planted in one of these grasses could show a two percent increase or more of organic matter. This can have profit benefits down the line.

Brassicas used as a cover crop are known as bio-fumigants (a method of destroying pests). Mustards are most commonly used as bio-fumigants against nematode and soil fungi problems. When bio-fumigating, the cover crop is chopped and immediately incorporated into the soil for best results. Chopping or mowing should be just prior to bloom.

Planting cover crops is a matter of purpose and need. Are you rotating in a cover crop to prevent weeds in a fallow field, scavenging nitrogen or building biomass and good bacteria? Plant in spring, mow it when it begins to flower, and plow under in the fall; plant in the late summer or early fall, over winter, then crimp or roll the cover crop to kill it in spring and plant through the thick mat of decomposing vegetation.

Oilseed Radish
Late summer is a good time to start thinking about what cover crops you will want to plant in your fields in the fall.  For example, a mix of cereal rye and Austrian winter peas (legume) planted in late October will be able to start establishing themselves and create a living cover that will protect your field through the winter, while also doing all the things mentioned in this article.  Then in the spring, the cover crop can be managed in whatever way works best for you. If you are fortunate enough to have access to a roller/crimper and a no-till drill, this is an excellent tool to manage the cover crop. Rodale nstitute has been working on perfecting this technique for many years. If you do not have access to this equipment, cutting the cover crop down and incorporating it into the soil with a tiller or other methods can also work.

With cover crops, timing is very important.  Planting too late in the fall can result in poor growth, thus a weak cover crop.  Your specific weather, climate zone, soil type, farming techniques and skills will play important roles in choosing when to plant and what cover crop to plant. Research the possibilities and find the cover crop that suits your farm and climate. The profit in the soil will pay off.

An excellent resource to learn more about cover crop is the Midwest Cover Crop Council webpage
( or the #9 SARE Handbook “Managing Cover Crops Profitably.” You can download the book for free or order it for $19.00 from the website.
(by Susan Jaster, Small Farm Outreach Worker, Lincoln University)

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